Known processes for preparation of cyclopropylethanol are, for example, (1) a process which comprises reacting homoallyl alcohol with diazomethane [J. Org. Synth. 43, 3496(1978)], (2) a process which comprises reacting butadiene with dibromocarbene to obtain 1,1-dibromo-2-vinylcyclopropane, debrominating the obtained product with metallic sodium-alcohol to synthesize vinylcyclopropane and subjecting the vinylcylopropane to hydroboronation-oxidation [J. Org. Synth. 32, 939(1967)], and (3) a process which comprises reacting lithium cyclopropylate and ethylene oxide [J. Am. Chem. Soc. 81, 4891(1959)].
The above process (1) uses an explosive diazomethane. The above process (2) has to use, to form dibromocarbene, bromoform, which is carcinogenic and also uses metallic sodium, which is explosive. The above process (3) uses a toxic gas of ethylene oxide. These processes are therefore all not industrially advantageous processes for preparation of cyclopropylethanol.
Known processes for preparation of cyclopropylacetonitrile are, for example, (4) a process which comprises reacting cyclopropylmethyl bromide in the presence of a phase transfer catalyst with an alkali metal cyanide in a solvent of water [WO00/63163], (5) a process which comprises reacting cyclopropylmethyl bromide with an alkali metal cyanide in dimethyl sulfoxide [J. Med. Chem. 13, 878(1970)], and (6) a process which comprises reacting cyclopropylmethyl bromide with an alkali metal cyanide in a solvent of ethanol [J. Am. Chem. Soc., 85, 932(1963)]. A process (7) is known for preparation of cyclopropanecarbonitrile, which comprises dehydrating cyclopropanecarbaldehyde oxime with formic acid [Tokuhyo-Hei 11-510487].
The above processes (4), (5) and (6), all using a toxic alkali metal cyanide, are not industrially advantageous processes for preparation of cyclopropylacetonitrile. The above process (7), which comprises neutralizing the reaction mixture obtained by the dehydration with an alkali metal compound, requires treatment of the effluent containing a large amount of the alkali metal formate byproduced on the neutralization. This process, when applied to preparation of cyclopropylacetonitrile, does not provide an industrially advantageous process.
Accordingly, an object of the present invention is to provide a process for preparing cyclopropylethanol at a low cost and industrially advantageously.
Another object of the present invention is to provide a process for preparing cyclopropylacetonitrile industrially advantageously.
Still another object of the present invention is to provide processes for preparing, industrially advantageously, intermediates for synthesizing cyclopropylethanol and cyclopropylacetonitrile.